Temp measurements in circulating BIAB

[turbo]

Hello,
I am moving into BIAB and have a 70l kettle (18 gal) and made a trial run with a grain bucket with a mesh in the bottom (made from a old fermenting bucket).
I was recirculating the wort with a temp probe in the inlet at the kettle pot lid and also temp probes in the wort (both down below the false bottom and in the wort bucket).
The temp was different by several degrees even though the wort was circulating, both + and + depending where I put the probes in the bucket.

Now I ordered a brew-bag (400 micron) that will remove the gap between the "grain bucket" and the pot wall and my question is if should it be expected to have big differences in temp between the probe under the false bottom, in the wort bag and in the inlet in the lid (after the pump)?

Also - should I mount the temp probe to steer the brew steps:

• Under the false bottom below the brew-bag
• On the output vent
• on the inlet after pump on the pot lid

Any advice would be greatly appreciated!

 

[Beer4All]

Hello,
I am moving into BIAB and have a 70l kettle (18 gal) and made a trial run with a grain bucket with a mesh in the bottom (made from a old fermenting bucket).
I was recirculating the wort with a temp probe in the inlet at the kettle pot lid and also temp probes in the wort (both down below the false bottom and in the wort bucket).
The temp was different by several degrees even though the wort was circulating, both + and + depending where I put the probes in the bucket.

Now I ordered a brew-bag (400 micron) that will remove the gap between the "grain bucket" and the pot wall and my question is if should it be expected to have big differences in temp between the probe under the false bottom, in the wort bag and in the inlet in the lid (after the pump)?

Also - should I mount the temp probe to steer the brew steps:

• Under the false bottom below the brew-bag
• On the output vent
• on the inlet after pump on the pot lid

Any advice would be greatly appreciated!

What are you using as a heat source and are you re-heating the mash during recirc (through a RIMS or HERMS)?

I have a recirculating BIAB/HERMS setup in a keggle and have a temp probe in the boil kettle and on the lid of the keggle (return from HERMS). These can vary by 1-2 degrees depending on a few factors.

 

[turbo]

I am using two heat elements on 2.2kW inside the pot.
I connected the heater elements to a PID and settled the temp to the wanted mash temp (67°C).
So I have a pump fed from the outlet valve on the kettle and pumping up to a nozzle under the lid.
In the lid I measure the temp and if it's <67°C the heater should kick in - does this seem reasonable?
I guess it's more of a RIMS style than HERMS but I figured it would work.
The wort was circulating fine but I had very different temperatures in different places in the port..

 

[Beer4All]

In the lid I measure the temp and if it's <67°C the heater should kick in - does this seem reasonable?

Yes. What PID are you using?

The wort was circulating fine but I had very different temperatures in different places in the port..

What are the variations you are seeing? If the set temp is 67C, what are you reading elsewhere? I would think the inlet back into the kettle would right at 67C or slightly above.

 

[turbo]

The PID is a MC901 with a PT100 sensor.
The other reading I get is about 62-64 in the wort when I put a probe in it and as low as 58-59 in the space between the pot walls and the "grain bucket". the spade around the bucket is quite big - 5-6 cm's on each side - perhaps this is what makes the temp diff.
I will make another try with the bag instead of the bucket and hope it gets more stable.

In your BAIB bag, are the temp reasonably distributed and equal throughout the mash?

 

[Beer4All]

The pt100 that is driving the pid controller is on the recirc line at the top correct? What probe are you using to check the temp in the wort? Another pt100 or some kind of an instant read? You could have an accuracy issue there. You are talking 5+ Deg F difference...

I only used the 400 micron Brew Bag once so far but I was really able to turn the pump up vs the traditional grain bed mash. I mashed at 152 and had 152 at the inlet of my kettle and 150-152 near the bottom of the kettle. This was for a 5 gallon batch in a keggle

 

[turbo]

Okey - thanks.
It was other temp probes I used, I have only one PT100 (3-wire model), the other was a temp meter with a typk k thermocouple and I also tested with a kitchen thermometer (Inkbird). I tested those the other day with a DS18B20 (connected to a Raspberry Pi) in a kettle from 20°C -100°C and they where off at top 2°C at any point sp I guess I might have what I hear is called "dead spots" in the mash - perhaps I need to stir a bit more..

I will make a more 'scientific' probe test in the weekend and take some notes.. it would be great to have a known reference but will try ice/boil and a few point in between..

 

[Beer4All]

Let me know what you find out. Type k thermocouples have about a 1 deg C error vs an rtd in the .3 deg C range.

 

[doug293cz]

You want to place the temp probe that is used to provide input to the PID near the heat source. If the probe is remote from the heater, then the wort near the heater can overheat - denaturing enzymes or even scorching the wort - before the remote temp probe & PID even know the temp has gotten too high.

You should characterize the temp deltas during an actual mash, as you may need to set your set point a bit higher than the desired mash temp. Insulating the recirculation plumbing can reduce the temp loss of the wort in the recirc loop.

Brew on

 

[Beer4All]

If you had suspected RTDs with a slight reading error, what would be your recommended way to test? Ice water and boiling tests?

 

[doug293cz]

If you had suspected RTDs with a slight reading error, what would be your recommended way to test? Ice water and boiling tests?

Ice water and boiling water are good test points. A proper ice bath is almost all crushed ice with minimum water - an ice cube in a glass doesn't cut it. If you are at an elevation significantly above sea level, you may need to correct for the lower boiling point.

If you have a known accurate thermometer, then it is easy to cross check your RTD's in solutions of various temperature. Calibrating near the temperature of interest (mash temps for use brewers) is usually the best way to go.

Brew on

 

[odie]

My probe is in the bottom of the basket about 1" about the element. I would rather the wort be a little cool than a bit too hot and denature the enzymes before full conversion.

My kettle has reflectix so not too worried about losing much heat. Bigger issue is too much heat in the mash IMO.

 

[turbo]

Thanks for your comments.
I will move the probe to the kettle outlet.
the diameter of the kettle is about 17", will it be likely that the wort will "channel" from the bag down to the outout and not "equal out"?
I dont plan to stir very much during the mash- o perhaps I should?
rims or herms I dont see make any difference to this topic..

 

[k-daddy]

The pt100 that is driving the pid controller is on the recirc line at the top correct? What probe are you using to check the temp in the wort? Another pt100 or some kind of an instant read? You could have an accuracy issue there. You are talking 5+ Deg F difference...

I only used the 400 micron Brew Bag once so far but I was really able to turn the pump up vs the traditional grain bed mash. I mashed at 152 and had 152 at the inlet of my kettle and 150-152 near the bottom of the kettle. This was for a 5 gallon batch in a keggle

I just purchased a Brewbag 400 micron bag for my 2 vessel, kettle rims setup where I recirculate wort between the MT & BK to maintain mash temps. I was wondering if I could tighten my grain mill, from .035 to somewhere between .025-.030 and not have too slow a recirculation or a stuck sparge. From your quote above, it seems like you had no problem with the recirculation. I have a Spike MT & false bottom and I'm thinking of switching to this Brewhardware FB Stainless Steel False Bottom for Brew In a Bag (BIAB) - 13'' Diameter to further aid in the flow. I'd be curious to know your thoughts. Seems many BIAB-ers don't recirculate making it harder to get information. Thanks.

 

[Beer4All]

I just purchased a Brewbag 400 micron bag for my 2 vessel, kettle rims setup where I recirculate wort between the MT & BK to maintain mash temps. I was wondering if I could tighten my grain mill, from .035 to somewhere between .025-.030 and not have too slow a recirculation or a stuck sparge. From your quote above, it seems like you had no problem with the recirculation. I have a Spike MT & false bottom and I'm thinking of switching to this Brewhardware FB Stainless Steel False Bottom for Brew In a Bag (BIAB) - 13'' Diameter to further aid in the flow. I'd be curious to know your thoughts. Seems many BIAB-ers don't recirculate making it harder to get information. Thanks.

I have done 3 brew days total with this setup. I have a keggle as the MT/BK in BIAB & a 10 gal HERMS kettle with the MKII pump. I have my mill as fine as it will go [around .030 I think. I reduced to .025 but couldn't get the grain to pull through the rollers - have a 2-roller mill]. With the 400 micron BrewBag I have no issues with clogging/stuck mash...that is running the pump with the output valve 100% open or 50% open. Has been working great...mash eff. in the 3 batches has been between 83-90%.

For your setup, you are using the RIMS to reheat you said? Do you have an electric element in the kettle you also plan to fire during the mash? If not you shouldn't need a false bottom at all.
The 15 gal keggle I have has a 5500W ripple element that I use to heat the strike water but after that is reached I just drop the BrewBag in and it forms around the element (you could not fire the element during mashing or you would burn the bag). I haven't had an issue so far & I had asked BrewBag about this before I bought and they told me plenty of people were doing the same thing.
Cheers!

 

[odie]

will it be likely that the wort will "channel" from the bag down to the outout and not "equal out"?
I dont plan to stir very much during the mash- o perhaps I should?

If you are full volume mash I think the wort level will be a few inches above the grain bed. the return hose can just dump into the top and it will just spread out. The pump is pulling wort from beneath the false bottom and the wort will flow thru the grainbed pretty evenly to replace the lost wort. You are only going to get a "channel" if your grain bed is at or just below the surface and the return flow is "drilling a tunnel" down.

I would put the controller probe on the false bottom centered above the element. This will be the hottest wort and right at the bottom of the grain bed. Use another thermometer to sample temps in the middle of the grain bed and the top of the wort as well if you like to compare and make adjustments. If it's too cold you can always add heat to help the enzymes. But if you torch the enzymes your mash is likely done and conversion incomplete.

Don't bother stirring. Recirc is doing that for you to keep mash temps uniform. People only stir because the wort is stagnate without recirc.

 

[k-daddy]

I have done 3 brew days total with this setup. I have a keggle as the MT/BK in BIAB & a 10 gal HERMS kettle with the MKII pump. I have my mill as fine as it will go [around .030 I think. I reduced to .025 but couldn't get the grain to pull through the rollers - have a 2-roller mill]. With the 400 micron BrewBag I have no issues with clogging/stuck mash...that is running the pump with the output valve 100% open or 50% open. Has been working great...mash eff. in the 3 batches has been between 83-90%.

For your setup, you are using the RIMS to reheat you said? Do you have an electric element in the kettle you also plan to fire during the mash? If not you shouldn't need a false bottom at all.
The 15 gal keggle I have has a 5500W ripple element that I use to heat the strike water but after that is reached I just drop the BrewBag in and it forms around the element (you could not fire the element during mashing or you would burn the bag). I haven't had an issue so far & I had asked BrewBag about this before I bought and they told me plenty of people were doing the same thing.
Cheers!

Thanks for your comment. I have a 5500w ripple element in the boil kettle and separate MT with a FB. Mash temps are regulated using a PID with the temperature probe located at the outlet of the BK close to the element so the mash won’t overheat. It’s basically a figure 8 pattern of recirculation. Trying to modify my process to be able to boost efficiency by crushing finer and help simplify cleanup. The thought of a stuck mash is my biggest concern.

 

[odie]

stuck mash is often a result of too much pump. the grain bed has a natural flow rate. no matter how loose or tight the crush it will flow. it's possible to be so tight and compacted that the "flow" is just dripping...but a dripping flow is useless for our needs, effectively "stuck".

too much pump effectively sucks the grain bed tighter. removing the wort from the grain bed results in the wort above the grain pushing down on the grain and compressing the voids that once contained wort but are now air pockets.

I would suggest using a very small pump to recirc during the mash. I use a tiny 12v magnetic pump. about $10 off ebay. it's the size of your car fob. even that can still out flow a tight mash.